{
  "abstract": "Although quadruply bonded metal-metal complexes constitute a large and well-established family, their cycloaddition chemistry remains underdeveloped because the quadruple bond is typically confined within a tetragonal, highly ligand-protected coordination environment. Herein, we demonstrate that a low-coordinate amidinate-supported W-W quadruple bond in W₂(μ-Cl)-(μ-κ²-Cl₂Li-(THF))-[μ-κ²-HC-(N-2,6- i Pr₂C₆H₃)₂]₂ behaves as an alkene surrogate in cycloaddition chemistry. Depending on ligand coordination, this W-W quadruple bond engages alkynes in either formal [2 + 2 + 2] or [2 + 2 + 1] pathways. In the absence of ancillary donor ligands, direct reaction with two alkynes proceeds through tail-to-tail [2 + 2 + 2] cycloaddition to afford C₄W₂ metallacycles, W₂Cl₂[μ-η²:η²-1,4-R₂C₄H₂]-[μ-κ²-HC-(N-2,6- i Pr₂C₆H₃)₂]₂ (R = C₆H₅, 2-MeC₆H₄, 4-MeOC₆H₄, and n-C₃H₇), and a corresponding [2 + 2] intermediate, W₂Cl₂[μ-η²-2-MeC₆H₄CCH]-[μ-κ²-HC-(N-2,6- i Pr₂C₆H₃)₂]₂, could be isolated and structurally characterized. In contrast, coordination of σ-donating ligands to the W-W core diverts the reaction pathway by stabilizing vinylidene intermediates, W₂Cl₂(C₅H₅N)-[μ-η¹:η²-CC-(H)-R¹]-[μ-κ²-HC-(N-2,6- i Pr₂C₆H₃)₂]₂ (R¹ = 2-MeC₆H₄, t Bu, and SiMe₃), which subsequently react with a second alkyne (R²CCH) to furnish C₃W₂ ring products of the type W₂Cl₂[μ-η²:η²-1-R²-4-R¹H-C₄H]-[μ-κ²-HC-(N-2,6- i Pr₂C₆H₃)₂]₂ bearing an exocyclic alkene fragment. In both [2 + 2 + 2] and [2 + 2 + 1] manifolds, while the initial cycloadducts adopt nonplanar conformations, sequential reduction populates the W-W δ manifold and drives planarization via δ-π conjugation between the W₂ unit and the organic fragment. Ultimately, the C₄W₂ systems are transformed into aromatic bimetallic metallabenzenes, [W₂(μ-κ²-1,4-R₂C₄H₂)-(μ-κ²-HC-(N-2,6- i Pr₂C₆H₃)₂)₂] (R = C₆H₅, 2-MeC₆H₄, 3-MeC₆H₄, 4-MeC₆H₄, 4-MeOC₆H₄, 4-FC₆H₄, and n-C₃H₇), whereas the C₃W₂ system evolves into a bimetallic fulvene analogue, W₂Cl-[μ-κ²-1-C₆H₅-4- t BuH-C₄H]-[μ-κ²-HC-(N-2,6- i Pr₂C₆H₃)₂]₂ and W₂(μ-H)-[μ-κ²-1-C₆H₅-4- t BuH-C₄H]-[μ-κ³-HC-(N-2,6- i Pr₂C₆H₃)-(N-2- i Pr-6-(C₃H₆)-C₆H₃)]-[μ-κ²-HC-(N-2,6- i Pr₂C₆H₃)₂]. Taken together, these results expand the scope of cycloaddition partners to include a low-coordinate W-W quadruple bond.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan."
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 7,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Wen-Chi Chen"
    },
    {
      "affs": [
        0
      ],
      "name": "Cian-Wei Yang",
      "orcid": "0000-0002-2334-6616"
    },
    {
      "affs": [
        0
      ],
      "name": "Bo-An Liao",
      "orcid": "0000-0003-2365-3736"
    },
    {
      "affs": [
        0
      ],
      "name": "Chiao-Yun Chen"
    },
    {
      "affs": [
        0
      ],
      "name": "Hong-Zhang Chen"
    },
    {
      "affs": [
        0
      ],
      "name": "Wen-Chuan Hsu"
    },
    {
      "affs": [
        0
      ],
      "name": "Yi-Chou Tsai",
      "orcid": "0000-0002-0857-6448"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/exqyt659yn637.bib",
  "cited_by": 0,
  "doi": "10.1021/jacsau.6c01251",
  "fulltext_url": "https://europepmc.org/articles/PMC13714859",
  "id": "exqyt659yn637",
  "issns": [
    "2691-3704"
  ],
  "landing_url": "https://europepmc.org/article/MED/42953580",
  "language": "eng",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "heading",
      "Article"
    ],
    [
      "openalex",
      "1605|Organometallic Complex Synthesis and Catalysis"
    ]
  ],
  "openalex": "W7214180679",
  "pdf_url": "https://europepmc.org/articles/PMC13714859?pdf=render",
  "pmcid": "PMC13714859",
  "pmid": "42953580",
  "published": "2026-09-24",
  "publisher": "American Chemical Society",
  "ris": "https://research.draconitic.com/paper/exqyt659yn637.ris",
  "sources": [
    {
      "first_seen": "2026-10-31T00:20:41Z",
      "native_id": "MED:42953580",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/42953580"
    },
    {
      "first_seen": "2026-11-01T12:22:16Z",
      "native_id": "PMC13714859",
      "source": "pmc",
      "url": "https://doi.org/10.1021/jacsau.6c01251"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "openalex:1605|Organometallic Complex Synthesis and Catalysis",
      "subfield": "organic"
    }
  ],
  "title": "Low-Coordinate W-W Quadruple Bond as an Alkene Surrogate: Divergent [2 + 2 + 2] and [2 + 2 + 1] Cycloadditions with Alkynes.",
  "title_text": "Low-Coordinate W-W Quadruple Bond as an Alkene Surrogate: Divergent [2 + 2 + 2] and [2 + 2 + 1] Cycloadditions with Alkynes.",
  "type": "peer-reviewed",
  "updated_at": "2026-11-01T12:22:16Z",
  "url": "https://research.draconitic.com/paper/exqyt659yn637",
  "venue": "JACS Au",
  "versions": []
}